Flu activity across the country ticked up slightly at the end of January but overall the toll from influenza this season is lower than it’s been in recent years.

Still, the Centers for Disease Control and Prevention are advising clinicians to treat suspected influenza in high-risk outpatients with antiviral medications as soon as possible. Don’t wait for testing results, the agency says, because early antiviral treatment works best.

The H1N1 viruses (which caused the 2009 flu pandemic) have predominated in recent weeks, landing some young- to middle-aged adults in intensive care from a severe respiratory illness. Fatalities have been reported, the CDC said. This strain of the virus has been known to cause severe illness in children and young adults.

At the ZipClinic Urgent Care centers in Colorado, General Manager Aniela Johnson said clinicians are seeing more patients come in with the flu. Some are reporting symptoms that aren’t as common, such as intense muscle pain without any fever. At ZipClinic in Belgrade, Montana, Admin Manager Tracey Joyner said the clinic is gearing up as nearby counties have been reporting more cases of the H1N1 flu.

“As always, we suggest patients get the vaccine (if they haven’t already), exercise good hand-washing habits, and stay home if they have flu-like symptoms,” Joyner said.

The CDC is reporting widespread flu activity in four states—California, Maryland, Massachusetts, and North Carolina. Regional flu activity is reported in Puerto Rico and 14 states. See a map here. The traditional flu season runs through May.

Here are a few of the general recommendations to keep in mind for patient treatment:

Clinicians should encourage all patients ages 6 months and older who have not yet received an influenza vaccine this season to be vaccinated against influenza.

When indicated, antiviral treatment should be started as soon as possible after illness onset, ideally within 48 hours of symptom onset. Clinical benefit is greatest when antiviral treatment is administered early. However, antiviral treatment might still be beneficial in patients with severe, complicated, or progressive illness.

Those at highest risk of flu complications include: children ages 2 and under, adults ages 65 and older, those with chronic conditions, pregnant women, and those with immunosuppression.